The present invention relates to an open-end rotor spinning machine, and more particularly to a fiber opening, fiber feeding and yarn withdrawing unit for a spinning station of an open-end rotor spinning machine.
In conventional open-end rotor spinning machines sliver is fed to a fiber opening roller from which the fibers are fed through a conduit into a rotating rotor that has an interior fiber collection groove and a frustoconical fiber slide wall converging from the collection groove to a reduced diameter open end, with the fibers being fed to the fiber slide wall on which they slide into the collection groove and are withdrawn as yarn through a central draw-off tube that is incorporated in the yarn feed conduit element. The fiber feed conduit includes a projection that extends into the rotor, but as it is necessary to periodically clean, maintain and replace the rotor and associated components, the fiber feed conduit must be constructed and mounted so that it can be removed from within the rotor and subsequently reinserted, which is conventionally accomplished by relative axial movement of the fiber feed conduit projection into and out of the rotor open end. For this reason, the fiber feed conduit projection must fit within the open end of the rotor and, therefore, must be of a shape and size such that it does not extend beyond the diametrical extent of the rotor open end. This requirement in combination with the frustoconical shape of the fiber slide wall, results in a considerable spacing between the end of the fiber feeding conduit and the fiber slide wall of the rotor, with the fibers passing through this spacing being free of positive contact with either the feed conduit or the rotor wall, such that the fibers are not subject to control in this spacing and can become disoriented with a resulting deleterious effect on the strength and quality of the yarn being spun.
This spacing is a function of the inclination of the conicity and extent of the slide wall and becomes proportionately greater in relation to the diameter of the rotor when smaller diameter rotors are used with the same extent and conicity of slide wall. As a result, there is a proportionately greater problem of fiber control in passing from the end of the fiber feed conduit through the spacing to the slide wall of the rotor and quality cannot be maintained as well at high draw-off speeds. In this regard, some fibers travel directly into the collection groove rather than slide along the slide wall, and also there is an increase in the likelihood of fibers being picked up on and forming wrapper fibers on the yarn being drawn-off, all reducing the strength and quality of the yarn. Further, the flow of fibers from the end of the fiber feed conduit fans out in the spacing such that the greater spacing in relation to the diameter of the rotor with a corresponding decrease in quality of the yarn produced.
In contrast, the present invention results in the production of high quality yarn at high rotor speeds and high draw-off speeds even with small diameter rotors, while avoiding the aforementioned disadvantages and increasing the spinning effectiveness.